Remote dictation system



Aug. 5', 1958' 1.. RIJONES ET AL REMOTE DICTATION SYSTEM Filed Dec. 3, 1956 D B FRANK H PALMER, Jr. z if I! r I ATTORN INVENTORS LLOYD R. JONES RUDOLF E. FREl/N REMGTE DHCTATIGN SYSTEM Lloyd R. Hones, tepney, Rudolf E. Freund, Bridgeport,

and Frank H. iaimer, L, Mitford, Conn, assignors to Bictaphone Corporation, Bridgeport, (Jenn, a cor= poration of New York Appiication December 3, 1956, Serial No. 625,714

9 Claims. (Cl. 179--6) This invention relates to remotely-operated dictation systems wherein a remote dictating station is connected to a centrally-located recording machine, as disclosed in the copending application of L. R. Jones et al., Serial No. 457,165, filed on September 20, 1954. More particularly, this invention relates to such systems wherein the dictating stat on is arranged to permit dictation by a person located a substantial distance, e. g. 5 or feet, away from the sound pick-up device associated with the dictating station.

It frequently is desired to employ remote dictation systems in situations where the microphone must be positioned a substantial distance away from the person or persons engaged in dictating to the central recording machine. For example, in connection with autopsy examinations at hospitals, it is the practice for a group of doctors and other persons to stand around the examination table and individually report their findings. T 0 make a permanent record of these findings, a microphone may be suspended from the ceiling over the examination table and arranged to pick up such comments as are made by the examining staff so that these comments may be transmitted to a central recording machine. It also is desirable during such an operation to be able to play back a portion of the recorded material periodically, and for this purpose a loudspeaker may be mounted in the examination room adjacent the table and connected to the dictation system so as to audibly reproduce the recorded a substantial distance away from the microphone and loudspeaker, it is important that the dictation system be arranged to have a relatively high gain in order to assure adequate signal levels for both recording and playback. This high gain, however, tends to produce regenerative oscillation due to feedback of sound signals from the loudspeaker to the microphone, because both of these units are coupled to a common transmission circuit leading to the central recording machine. Accordingly, special provisions must be made to avoid such regenerative oscillation.

in addition, it is desirable to provide means at the central recording machine to produce warning signals and the like which are transmitted back to the remote dictator to apprise him of certain operating conditions of the machine, e. g. that the end of the record is approaching. The system should be arranged so that these signals may be heard over the loudspeaker during a recording operation, without at the same time producing regenerative feedback between the loudspeaker and the microphone, and also without destroying the intelligi bility of the recording.

Accordingly, it is an object of this invention to provide an improved remote dictation system. It is a further object of this invention to provide such a system that is especially adapted for use in situations where the dictator is located a substantial distance from the micro- ECQ phone unit. It is a still further object of this invention to provide a remote dictation system having characteristics as set forth hereinabove. Other objects, aspects and advantages of this invention will be in part apparent from, and in part pointed out in, the following description of a preferred embodiment of the invention considered together with the accompanying drawing which is a schematic circuit diagram of this embodiment.

Referring now to the upper right-hand corner of the 1 drawing, there is shown in dotted outline a dictating station 10 which is essentially identical to the dictators instrument of Figure 1A in the above-mentioned copending application of L. R. Jones et al. This station is connected by four leads 12, 14, 16 and 18 to the control and recording apparatus (not shown herein) of the remote dictation system; this control and recording apparatus is shown in Figures 1B through 1B of the abovementioned application, wherein the corresponding four interconnecting leads also are identified by the same reference numerals 12, 14, 16 and 18. It will be understood that the system normally includes a number of identical dictating stations 10, all connected in parallel to the four interconnecting leads, although only one such sta tion is shown herein in order to simplify the description.

The dictation system is activated for operation by an on-off switch 24 in the station it) (which serves the same function as the cradle switch 24 shown in the abovementioned application). As explained in that application, actuation of this on-ofi switch completes an audio communication current from within the station 10 and through leads 12 and 14 to the central recording machine. This circuit may be traced from the lead 12 through contacts 19 of a privacy relay 20 (which serves to exclude other dictating stations from the audio communication circuit once the central recording machine has been activated by one station), through a resistor 21 to a dummy load resistor 22 (which takes the place of the microphone 22 shown in the above-mentioned application), through contacts 23 of an attendants call switch 25 (operation of which serves to signal the attendant at the central recording machine), through contacts 26 of the privacy relay and contacts 27 of the on-off switch 24 back to lead 14. Also as explained in the above-mentioned application, completion of this audio circuit causes a lowlevel direct current to flow throughthe circuit, including leads 12 and 14, to operate a control relay (not shown herein) which connects energizing potential to the central recording machine.

After the system has thus been activated for operation, recording may be initiated (referring now to the lower right-hand portion of the drawing) by closing a switch 23 which may, for example, be operated by the dictators foot or knee. Operation of this switch energizes a record relay 29 through a circuit which may be traced from the negative terminal 30 of a D.-C. power supply 31, along a lead 32, through the winding 33 of the record relay and back to a positive terminal 34 of the power supply. Contacts 35 of the record relay close and place a short circuit across the resistor 21 and a resistance-capacitance noise-suppression network 21a con-' nected in parallel therewith. Shorting out this resistor 21 causes a substantial increase in the level of direct current flowing through the leads 12 and 14, and this in creased current is arranged to actuate another control relay (see the above-mentioned application) which in turn operates the recording machine clutch and thereby conditions this machine for recording.

Referring now to the upper left-hand corner of the drawing, a pick-up microphone 36, which may for example be suspended over an autopsy examination table, is electrically coupled through a transformer 33 and a capacitor 40 to the control grid of a pentode amplifier tube generally indicated at 42. The suppressor grid and cathode of this tube are connected together and, through a resistance-capacitance network 44, to a common ground lead 46 which returns to the negative terminal Bil of the power supply 31. The plate of the tube 42 is energized through a load resistor 48, an isolation resistor d and a lead 52 which is connected to a positive high-voltage terminal 54 of the D.-C. power supply 31. The screen grid is energized through a network including two series resistors 56 and 58 and a capacitor 60, and a decoupling capacitor 61 is provided to prevent interaction through the common power supply connection with succeeding stages of amplification.

Signal variations on the plate of this pentode tube 42 are fed through a coupling capacitor 62 and a potentiometer 64 to the input of an amplifier having two triode stages 66 and 68. The cathode of the first tube 66 is returned to ground through a resistance-capacitance biasing network 79, and its plate is supplied with energizing potential through a load resistor 72 the other end of which is connected to the high-voltage lead 52. The plate of this first tube is coupled through a capacitor 74 to the control grid of the second tube 63, and the plate of this latter tube is energized through the primary winding of an audio transformer 75 and the high-voltage lead 52.

The cathode of the second tube 68 is returned to the common ground lead 46 through a resistance-capacitance biasing network 76, a lead 78, and contacts $0 of the record relay 29 which is energized when the system is conditioned for recording. When the switch 28 is released, of course, the record relay drops out and the cathode of tube 68 is disconnected from ground so that no signals will be transmitted from the microphone 36 to the audio transformer '75.

With the system conditioned for recording, audio signals are coupled from the secondary of the transformer 75 through a pair of capacitors 82 and 84, through the dictating station 10, and out to the transmission leads 12 and 14 to the' recording head of the central recording machine. This circuit may be traced from the upper capacitor 32 down along a lead 86, through the contacts 35 of the record relay 29,'through the contacts 99 of a correction mark switch 92 (which when operated conditions the recording machine to make a mark on the indicator slip typicallyusedwith dictating machines), -through an inductor 94 and contacts 19 of the privacy relay to lead 12, and back from lead 14 through contacts 27 of the on-off switch 24, contacts 26 of the privacy relay, and contacts 23 of the attendants call switch to the lower coupling capacitor 84.

Accordingly, it will be apparent that, during recording operations, voice signals transmitted from the microphone 36 will be amplified by the three amplifier stages 42, 66 and 68 and fed through the dictating station it) to the transmission leads 12 and 14, from which these signals ultimately are coupled to the recording head of the central dictating machine. Because the dictator may not always be the same distance away from the microphone during recording, and for other reasons to be explained, the amplification gain provided by these three stages is controlled by a forward-acting automatic volume control circuit which will now be described.

Signal variations on the plate ofthe pentode amplifier tube 42 are fed through a lead 110, a coupling capacitor '112 and an input resistor 1 4 to an amplifier comprising two triode stages116 and 118. The cathodes of both tubes 116 and 118 are connected to the ground lead 46 through resistance-capacitance biasing networks 122 and 124, and the plates of these tubes'are energized through load resistors 12 5 and 123 which are connected to the high-voltage lead 52. The plate of the first tube 116 is coupled through a capacitor 139 to the grid of the 4 second tube 118, and this latter grid is returned to ground through an input resistor 132.

The plate of the second tube 118 is coupled through a capacitor 134 to a rectification circuit including a pair of half-wave rectifiers 136 and 138 and a load resistor 1421. A negative direct-current voltage is developed across this load resistor in accordance with the amplitude of the signal fed to the amplifier 116, and this direct-current voltage is fed through a filter network comprising a pair of shunt capacitors 142 and 144 and a series resistor 146, and through an isolating resistor 147 to the control grid of the pentode amplifier tube 42. The resulting negative feedback action produced by the amplifier stages 116 and 118 controls the efiective gain of the main amplifier stage 42 so as to avoid overloading the system when a dictator speaks loudly or close by the microphone 36, and tends to prevent suddent largeamplitude signal peaks. Such signal peaks also are minimized by filter capacitors 148 and 143 connected between ground and the plates of the amplifier tubes 4-2 and 66 respectively.

The system may be conditioned to play back recorded material by first releasing the switch 28, thereby 'deenergizing the record relay 29, and then actuating a playback switch 154 in the dictating station 19. As explained in the above-mentioned application, actuation of the playback switch operates relays (not shown herein) to condition the system in such manner that previously recorded material is fed back along the transmission leads 12 and 14 to the dictating station. These playback signals pass through the dictating station to the audio transformer 75, (It may be noted that the playback circuit through the dictating station is the same as the recording circuit except that the signals pass through the upper contacts of the playback switch 150'rather than through the contacts 35 of the record relay 29 which of course is (fie-energized during playback.)

These playbacksignals are fed from the primary of the audio transformer 75 down along a lead 152, through a coupling capacitor 154 and a potentiometer 156 to the control grid of a pentode amplifier tube generally indicated at 158. The suppressor grid and cathode of this latter tube are connected together and, through a resistancecapacitance biasing network 160 and contacts 162 of the record relay 29, to the common ground lead ,46. The plate of this tube 158 is connected to one end of the primary winding of an output audio transformer 164, the other end of the primary winding being connected to the screen grid and also to a high-voltage terminal 166 of the D.-C. power supply 31. The secondary winding of the transformer 164 is connected to a loudspeaker generally indicated at '170. Thus, the playback signals fed through the dictating station 10 are amplified by the tube 158 and transmitted to the loudspeaker 170 so that the dictator, and others nearby, may hear what has been recorded.

As described in the above-mentioned application, certain information signals are produced by the central recording apparatus and fed back to the remote dictating station, e. g. to warn the dictator that the end of the record is approaching. in the present embodiment, these signals are in the form of short bursts of tone having a frequency of 2500 cycles per second and a duration of 200 milliseconds. The system disclosed herein is adapted to feed these tone signals out through the loudspeaker 170 while recording is in progress.

These tone signals are fed from the leads 12 and 14 through the dictating station 10 (through the circuit path traced hereinabove) to the audio transformer '75, down the lead 152 and (referring now to the lower left-hand corner of the drawing) through a coupling capacitor 172 and a resistor 174 to a tuned circuit comprising an inductor 176 and a capacitor 178. This latter circuit is sharply tuned to the frequency of the warning tube, i.- e. 2500 cycles per second, and thus feeds the warning tone to the input of an amplifierhaving two triode stages 125i? and 182. The grid of the first tube 180 is returned to ground through the usual input resistor lit-t and the cathodes of both tubes are connected to ground through respective resistance-capacitance biasing networks 136 and 188.

The plate of the first stage 180 is connected through a load resistor 190, a positive voltage lead 192 and contacts 194 of the record relay 29 to a positive voltage terminal 196 of the D.-C. power supply 31. This plate also is coupled through a capacitor 198 to a rectifier circuit comprising a pair of half-wave rectifiers 201} and 202. The resulting output of this rectifier circuit is a positive ill-C. Voltage which is fed to the control grid of the second tube 182 through a network comprising a shunt capacitor 204!- and a pair of resistors 206 and 208.

The plate of the second amplifier tube 182 is connected through the winding 210 of a warning relay 212 to the positive voltage lead 192. Thus, when a warning tone of proper frequency is transmitted to the input of the amplifier stage 180, current flows through the relay winding 210 and this relay is actuated for the duration of the warning tone. Consequently, relay contacts 21 2- close to place a short circuit across the input resistor 216 of the recording amplifier stage 68 thereby disables this amplifier so that no signals can be transmitted from the microphone 36 to the audio transformer '75. Closure of the other relay contacts 213 activates the loudspeaker amplifier 158 by completing a circuit between the common ground lead 46 and the resistance-capacitance network 160. A resistance-capacitance noise-suppression network 219 is connected across these latter contacts to prevent relay clicks from being fed to the loudspeaker amplifier.

The tone pulses, as in the case of playback signals transmitted from the central recording machine, also are fed from the audio transformer 75, down along lead 152'; and through the coupling capacitor 154 and potentiometer 156 to the control grid of the loudspeaker amplifier 158. Since this amplifier is activated by the warning relay 212 during the warning pulse, these tone signals are converted to audible sound signals by the loudspeaker 17% to be heard by the dictator and others nearby.

The warning tone pulses fed through the audio transformer 75 have a much higher signal level than the voice signals normally fed through this transformer from the microphone 36, and hence there is very little tendency for the warning relay 212 to be actuated by 250-!) C. P. S. components of the voice signals. Furthermore, this tendency is efiectively minimized by the automatic-volumecontrol circuitry described above, which serves to maintain a relatively constant level of voice signals, and also by the filter capacitors 142 and 149 in the amplifier stages 42 and 66. In addition, operation of the Warning relay is delayed a few milliseconds after receipt of an input signal to the amplifier 18%, so that any short-duration peaks that reach this amplifier will not operate the relay and disable the recording circuit. This delay is produced by the shunt capacitor 204- (in the input circuit of the amplifier 182) which takes a few milliseconds to charge up through the relatively high output impedance of the amplifier 180.

Although a specific preferred embodiment of the invention has been set forth in detail, it is desired to emphasize that this is not intended to be exhaustive or necessarily limitative; on the contrary, the showing herein is for the purpose of illustrating one form of the invention and thus to enable others skilled in the art to adapt the invention in such ways as meet the requirements of particular applications, it being understood that various modifications may be made without departing from the scope of the invention as limited by the prior art.

We claim:

1. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote ,6 dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indieating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to produce usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a loudspeaker mounted in proximity to said microphone to produce hi gh-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio frequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means arranged when actuated to interrupt the coupling between said microphone and said transmission circuit,.

said first switch means normally being de-actuated during recording of dictation from said microphone, second switch means arranged when actuated to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being actuated during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, and control means coupled to said transmission circuit and responsive during recording to the information signals developed by said signal-producing means, said control means being arranged when operated to actuate said first switch means and deactuate said second switch means, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is uncoupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone. I

2. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency warning signals through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to produce usable-output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, amplifier means forming part of said circuit means to-provide high signal levels for recording through said microphone and listening from said loudspeaker, first switch means arranged when actuated to interrupt the coupling between said microphoneand said transmission circuit, said first switch means normally being de-actuated during recording of dictation from said microphone, second switch means arranged when actuated to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being actuated during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, and control means coupled to said transmission circuit and responsive during recording to the warning signals developed by said signal-producing means, said control means being arranged when operated to actuate said first switch means and de-actuate said second switch means, whereby said warning signals are fed to said loudspeaker to develop audible sounds corresponding to said warning signals and said microphone is uncoupled from said, transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone.

3. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station, to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a micro phone to produce usable output signals in response to dictation from a person located a substantial distance away "therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a first amplifier forming part of said first circuit means, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fedthereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, a second amplifier forming part of said second circuit means, first switch -means arranged when actuated to interrupt the coupling from said microphone through said first amplifier to said transmission circuit, said first switch means normally being de-actuated during recording of dictation from said microphone, second switch means arranged when actuated to interrupt the coupling from said transmission circuit through said second amplifier to said loudspeaker, said second switch means normally being actuated during recording of dictation from said microphone so as to prevent regenerativefeedback between said loudspeaker and said microphone, and control means coupled to said transmission circuit and responsive during recording to the information signals'developed by said signal-producing means, said controlmeans being arranged when operated to actuate said first switch means and'de-actuate said second switch means, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is uncoupled from said trans mission circuit to prevent regenerative feedback between said loudspeaker and said microphone.

-4. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording headto transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recordercondition control device at said dictating station arranged to transmit recorder conditioning signals through saidtransmission circuit to said control apparatus for establishing selected modes of operation of said recordingapparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microT phone to produce-usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means having first and second positions and arranged when in said second position to interrupt the coupling etween said microphone and said transmission circuit, said first switch means normally being in said first position during recording of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said mi rophone so as to prevent regenerative feedback between said loudspeaker and said microphone, and control means coupled to said transmission circuit and responsive during recording to the information signals developed by said signal-producing means, said controltmeans being arranged when operated to move said first switch means to its second position and move said second switch means to its second position, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is uncoupled from said transmission circuitto pre-' vent regenerative feedback between said loudspeaker and said microphone.

5. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station'to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through saidtransmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus,

signal-producing means at said recording apparatus 'for feeding fixed audio-frequency warning signal pulses of short duration through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to produce usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means having first and second positions and arranged when in said second position to interrupt the coupling between said microphone and said transmission circuit, said first switch means normally being in said first position during recording of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, a tuned circuit coupled to said transmission circuit and having a resonant frequency substantially equal to the frequency of the warning signal pulses fed through said transmission circuit, and control means coupled to the output of said tuned circuit and responsive during recording to the warning signals developed by said signal-producing means, said control means being arranged when operated to move said first switch means to its second position and move said second switch means to its second position, whereby said warning signals are fed to said loudspeaker to develop audible sounds corresponding to said warning signals and said microphone is uncoupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone.

6. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indicat ing a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to produce usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, an amplifier forming part of said first circuit means, an automaticvolume-control feedback circuit for said amplifier to maintain a nearly constant level of signal fed to said transmission circuit by said microphone, a loudspeaker mounted in proximity to said microphone to produce high-vohune sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audiofrequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means having first and second positions and arranged when in said second position to interrupt the coupling between said microphone and said transmission circuit, said first switch means normally being in said first position during record- .ing of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, and control means coupled to said transmission circuit and responsive during recording to the information signals developed by said signalproducing means, said control means being arranged when operated to move said first switch means to its second position and move said second switch means to its second position, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is uncoupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone.

7. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on saidrecord, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to trans mit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing appa ratus associated with said dictating station comprising a microphone to produce usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means having first and second positions and arranged when in said second position to inte rupt the coupling between said microphone and said transmission circuit, said first switch means normally being in said first position during recording of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, control means coupled to said transmission circuit and responsive during recording to the information signals developed by said signal-producing means, and means associated with said control means to delay the operation thereof for a short time after receipt of a signal from said transmission circuit so that said control means will not be operated by sharp signal peaks produced by said microphone, the delay time being substantially less than the duration of said information signals, said control means being arranged when operated by said information signals to move said first switch means to its second position and move said second switch means to its second position, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is 7 11 uncoupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone. a

8. For use with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative traveling movement with respect to a record, a remote dictating station coupled to said recording head to transmit sound signals thereto for recording on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing selected modes of operation of said recording apparatus, signal-producing means at said recording apparatus for feeding audio-frequency information signals through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to produce usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, an amplifier forming part of said first circuit means, an automaticvolume-control feedback circuit for said amplifier to maintain a nearly constant level of signal fed to said transmission circuit by said microphone, a loudspeaker mounted in proximity to said microphone to produce high-volume sound signals in response to audio-frequency signals fed thereto, second circuit means for coupling said loudspeaker to said transmission circuit to permit audio-frequency signals from said signal-producing means to be reproduced over said loudspeaker, first switch means having first and second positions and arranged when in said second position to interrupt the coupling between said microphone and said transmission circuit, said first switch means normally being in said first position during recording of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said mi crophone so as to prevent regenerative feedback between said loudspeaker and said microphone, control means coupled to said transmission circuit and responsive dur ing recording to the information signals developed by said signal-producing means, and means associated with said control means to delay the operation thereof for a short time after receipt of a signal from said transmission circuit so that said control means will not be aperated by sharp signal peaks produced by said microphone, the delay time being substantially less than the duration of said information signals, said control means being arranged when operated by said information sig nals to move said first switch means to its second position and move said second switch means to its second position, whereby said information signals are fed to said loudspeaker to develop audible sounds corresponding to said information signals and said microphone is run coupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone.

9. For uses with a remotely-operated dictation system which includes centrally-located recording and control apparatus having a recording head arranged for relative travelling movement with respect to a record, a remote dictating station coupled to said recording head to trans mit sound signals thereto forrecording .on said record, a transmission circuit for connecting said station to said recording and control apparatus, a recorder condition control device at said dictating station arranged to transmit recorder conditioning signals through said transmission circuit to said control apparatus for establishing se lected modes of operaiton of said recording apparatus, signal-producing means at said recording apparatus for feeding short-duration tone pulses through said transmission circuit to said dictating station for indicating a predetermined condition of said recording and control apparatus; in combination, sound transducing apparatus associated with said dictating station comprising a microphone to product usable output signals in response to dictation from a person located a substantial distance away therefrom, first circuit means for coupling said microphone to said transmission circuit so that sound signals may be fed from said microphone through said transmission circuit to said recording head, an amplifier forming part of said first circuit means, an. automaticvolurne-control feedback circuit for said amplifier to maintain a nearly constant level of signal fed to said transmission circuit by said microphone, a loudspeaker mounted in proximity to said microphone to produce high volume sound signals in response to audio-frequency signals fed thereto, secondcircuit means for coupling said loudspeaker to said transmission circuit to permit audiofrequency signals from said signal-producing means to be reproduced over said loudspeaker, an amplifier form ing part of said second circuit means, first switch means having first and second positions and arranged when in said second position to interrupt the coupling between said microphone and said transmission circuit, said first switch means normally being in said first position during recording of dictation from said microphone, second switch means having first and second positions and arranged when in said first position to interrupt the coupling between said loudspeaker and said transmission circuit, said second switch means normally being in said first position during recording of dictation from said microphone so as to prevent regenerative feedback between said loudspeaker and said microphone, a tuned circuit coupled to said transmission circuit and tuned tothe frequency of said tone pulses, a control relay coupled to the output of said tuned circuit and responsive during recordingto the information signals developed by said signal-producing means, and time delay means for said control relay to prevent the operation thereof due to sharp signal peaks, the delay time being substantiallyless than the duration of said tone pulses, said control relay being arranged when operated by said tone pulses to move said first switch means to its second position and movesaid second switch means to its second position, whereby said tone pulses are fed to said loudspeaker to develop audible sounds corresponding thereto and said microphone is uncoupled from said transmission circuit to prevent regenerative feedback between said loudspeaker and said microphone for the duration of said pulses.

No references cited. 

